Positioning and stabilising structure for a patient interface

Abstract

A patient interface includes a positioning and stabilising structure having headgear comprising a ring strap portion with a superior portion configured to overlay the parietal bones of the patient's head in use and an inferior portion configured to overlay or lie inferior to the occipital bone of the patient's head in use. The ring strap portion defines a loop having a pair of upper strap portions configured to connect between the ring strap portion and a cushion assembly in use on a respective side of the patient's head superior to an otobasion superior. The headgear may comprise a rigidised portion. The headgear may be integrally formed by flat knitting and the strap portions may include blind guides to provide tactile indications of the locations of fastening portions.

The invention claimed is: 
     
       1. A patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to a patient's airways including at least an entrance of a patient's nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH2O to about 30 cmH2O above ambient air pressure in use, throughout a patient's respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing; said patient interface comprising:
 a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH2O above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient, 
 a seal-forming structure constructed and arranged to form a seal with a region of a patient's face surrounding an entrance to the patient's airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient's nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient's respiratory cycle in use; 
 a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient's head, the positioning and stabilising structure comprising a tie, the tie being constructed and arranged so that at least a portion overlies a region of the patient's head superior to an otobasion superior of the patient's head in use; and 
 a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient air, said vent structure being sized and shaped to maintain the therapeutic pressure in the plenum chamber in use; 
 wherein the patient interface is configured to allow the patient to breathe from the ambient air through the patient's mouth in the absence of the flow of air through the plenum chamber inlet port, or the patient interface is configured to leave the patient's mouth uncovered; 
 wherein the positioning and stabilising structure comprises: 
 a knitted ring strap portion having a superior portion configured to overlay the parietal bones of the patient's head in use and having an inferior portion configured to overlay or lie inferior to the occipital bone of the patient's head in use, the ring strap portion defining a loop and having an inside periphery and an outside periphery; and 
 a pair of upper strap portions, each configured to connect between the ring strap portion and a cushion assembly in use on a respective side of the patient's head superior to the otobasion superior; 
 wherein the ring strap portion comprises a first knit structure forming a first portion extending along at least a portion of the outside periphery of the ring strap portion, 
 wherein the ring strap portion comprises a second rigidised knit structure forming a second rigidised portion provided proximate the inside periphery of the ring strap portion, and 
 wherein the first knit structure is a different knit structure than the second rigidised knit structure, and the first portion has increased stretchability as compared to the second rigidised portion. 
 
     
     
       2. The patient interface of  claim 1 , wherein the second rigidised portion is provided substantially along the entire length of the loop defined by the ring strap portion. 
     
     
       3. The patient interface of  claim 1 , wherein the first portion extends along the entire outside periphery of the ring strap portion. 
     
     
       4. The patient interface of  claim 3 , wherein the second rigidised portion defines at least a portion of the inside periphery of the ring strap portion. 
     
     
       5. The patient interface of  claim 3 , wherein the second rigidised portion forms substantially the entire inside periphery of the ring strap portion. 
     
     
       6. The patient interface of  claim 1 , wherein the first portion is directly adjacent the second rigidised portion. 
     
     
       7. The patient interface of  claim 1 , wherein the upper strap portions are stretchable. 
     
     
       8. The patient interface of  claim 1 , wherein the second rigidised portion is substantially non-stretchable. 
     
     
       9. The patient interface of  claim 1 , wherein the ring strap portion comprises rounded edges. 
     
     
       10. The patient interface of  claim 1 , wherein the second rigidised portion comprises an increased material thickness relative to regions of the ring strap portion other than the second rigidised portion. 
     
     
       11. The patient interface of  claim 10 , wherein a patient-contacting side of the ring strap portion is substantially flat and the increased material thickness is provided to a non-patient-contacting side of the ring strap portion. 
     
     
       12. The patient interface of  claim 10 , wherein the ring strap portion comprises a thickness of 4 mm in the second rigidised portion. 
     
     
       13. The patient interface of  claim 10 , wherein the ring strap portion comprises a thickness of 2.5 mm in regions of the ring strap portion other than the second rigidised portion. 
     
     
       14. The patient interface of  claim 1 , wherein the second rigidised portion is larger in regions of the ring strap portion relatively proximate the upper strap portions than in regions of the ring strap portion relatively distal to the upper strap portions. 
     
     
       15. The patient interface of  claim 14 , wherein the second rigidised portion is wider in the regions of the ring strap portion relatively proximate the upper strap portions than in the other regions of the ring strap portion relatively distal to the upper strap portions. 
     
     
       16. The patient interface of  claim 1 , wherein the ring strap portion comprises at least one ventilation portion structured and/or arranged to provide increased breathability through the ring strap portion at the ventilation portion. 
     
     
       17. The patient interface of  claim 16 , wherein the ventilation portion comprises a knitted fabric having a pique mesh knitting structure. 
     
     
       18. The patient interface of  claim 16 , wherein stretchability in the ventilation portion is less than stretchability in regions of the ring strap portion other than the ventilation portions. 
     
     
       19. The patient interface of  claim 16 , wherein the second rigidised portion surrounds the ventilation portion. 
     
     
       20. The patient interface of  claim 16 , wherein the ring strap portion comprises a pair of superior ventilation portions, each provided proximate a respective upper strap portion of the pair of upper strap portions. 
     
     
       21. The patient interface of  claim 20 , wherein the second rigidised portion surrounds each of the superior ventilation portions. 
     
     
       22. The patient interface of  claim 21 , wherein the second rigidised portion comprises a higher material thickness on a posterior side of each of the superior ventilation portions than on an anterior side of each of the superior ventilation portions. 
     
     
       23. The patient interface of  claim 1 , wherein the positioning and stabilising structure comprises a pair of lower strap portions, each lower strap portion configured to connect between the ring strap portion and the cushion assembly in use on a respective side of the patient's head inferior to the otobasion superior. 
     
     
       24. The patient interface of  claim 23 , wherein the ring strap portion comprises an inferior ventilation portion provided between the pair of lower strap portions. 
     
     
       25. The patient interface of  claim 24 , wherein the inferior ventilation portion comprises an inferior edge spaced from an inferior edge of the ring strap portion. 
     
     
       26. The patient interface of  claim 25 , wherein the inferior edge of the inferior ventilation portion comprises a greater curvature than the inferior edge of the ring strap portion to create a maximum spacing between the inferior edge of the inferior ventilation portion and the inferior edge of the ring strap portion at or proximate a sagittal plane of the patient's head in use. 
     
     
       27. The patient interface of  claim 23 , wherein the lower strap portions are stretchable. 
     
     
       28. The patient interface of  claim 1 , wherein the entire ring strap portion comprises a knitted fabric structure. 
     
     
       29. The patient interface of  claim 28 , wherein the ring strap portion is formed by flat knitting. 
     
     
       30. The patient interface of  claim 28 , wherein the ring strap portion comprises a single jersey knitting structure. 
     
     
       31. The patient interface of  claim 28 , wherein the ring strap portion comprises a double jersey loop formation knitting structure. 
     
     
       32. The patient interface of  claim 28 , wherein the second rigidised portion comprises a pique knitting structure. 
     
     
       33. The patient interface of  claim 1 , wherein the superior portion of the ring strap portion comprises a pair of overhead strap portions adjustably connected to each other proximate a sagittal plane of the patient's head. 
     
     
       34. The patient interface of  claim 33 , wherein the overhead strap portions are adjustably connected with a buckle. 
     
     
       35. The patient interface of  claim 33 , wherein the overhead strap portions comprise hook and loop fastening material to allow each of the overhead strap portions to be passed through a portion of the buckle and secured back onto itself. 
     
     
       36. The patient interface of  claim 1 , wherein the positioning and stabilising structure comprises a frame coupled to the plenum chamber, the upper strap portions being configured to connect to the frame.